Formation of well packers

ABSTRACT

A well packer including a sleeve disposed about a pipe or other carrier structure and adapted to be compressed axially in a manner expanding the sleeve radially outwardly to form a seal in a well. The sleeve has a longitudinally central portion of relatively soft elastomeric material and two opposite end portions of harder elastomeric material, with annular plates desirably being provided between the end portions and the softer central body. In manufacturing the sleeve, a thin outer layer of relatively hard elastomer is provided about the body of softer material in order to allow accurate shaping of the outer surface of the packer at the location of the soft material, by machining the thin outer layer at that location to a desired circular cross section.

I United States Patent [191 [111 3,776,561 Haney Dec. 4, 1973 [54] FORMATION OF WELL PACKERS Primary Examiner-Samuel B. Rothberg [76] Inventor: Robert L. Haney, 111 Massey PL, smth S.W., Calgary, Alberta, Canada Attorney-wl ham R Green [22] Filed: Oct. 16, 1970 [57] ABSTRACT [21 Appl. No.: 81,412 A well packer including a sleeve disposed about a pipe or other carrier structure and adapted to be compressed axially in a manner expanding the sleeve radi- (g1. y outwardly to form a Seal in a we". The Sleeve has [58] Fie'ld 1251116 2 a longitudinally central portion of relatively soft elas- H16 8 tomeric material and two opposite end portions of harder elastomeric material, with annular plates desir- [56] References Cited ably being provided between the end portions and the softer central body. In manufacturing the sleeve, a UNITED STATES PATENTS thin outer layer of relatively hard elastomer is prol,788,109 1/1931 Jett 277/228 vided about the body of softer material in order to 2,612,953 10/1952 Morgan e1 277/116-2 allow accurate shaping of the outer surface of the g i at a i packer at the location of the soft material, by machin- 2808889 $1957 23 22: 277;]16'4 ing the thin outer layer at that location to a desired Ree-m circular cross section 9 Claims, 5 Drawing Figures PATENTEDUEB 41973 m all/I INVENTOR,

FORMATION OF WELL PACKERS BACKGROUND OF THE INVENTION This invention relates to improved well packer sleeves, and unique methods of manufacturing such sleeves.

A conventional type of well packer includes a tubular sleeve of rubber which is disposed about a rigid carrier structure such as a well pipe or rod, and which is expansible radially outwardly to a sealing position by axial compression of the sleeve. Such packer sleeves, as heretofore produced, have been fairly effective in forming seals within well spaces of limited radial or horizontal dimension, but have proven incapable of controlled expansion to an extent satisfying many of the sealing requirements encountered in larger diameter holes. This is particularly true when employing the packer within an uncased well, in which several inches of expansion may be required in order to engage and form a seal with an eroded or caved in portion of the well bore. When an attempt is made to expand most conventional packers radially outwardly far enough to engage a highly oversized hole of this type, the expansion quickly reaches an uncontrollable stage in which some of the rubber of the packer bulges axially rather than radially, in an unpredictable manner efiectively precluding any possibility of forming an adequate seal with the well bore wall. Some attempts have been made to improve the controllability of the expansion by use of elastomeric material of different hardnesses in a single packer assembly, but none of these prior expedients of which I am aware has proven sufficiently effective in actual use to have attained any wide scale acceptance in the field.

SUMMARY OF THE INVENTION The present invention provides a novel elastomeric packer sleeve which is of the above discussed general type but is capable of controlled and confined expansion to a degree much greater than that attained with prior packer sleeves, and which therefore permits formation of a seal in a well at large diameters heretofore felt impractical. At the same time, however, the sleeve is constrictable resiliently to a very small normal diameter for initial movement into the well, and for withdrawal upwardly from the well after use. Structurally, a sleeve embodying the invention has a main longitudinally central portion formed of a relatively soft elastomeric material capable of very great expansion, and has two opposite end portions formed on harder elastomeric material, whose presence acts to predetermine the location at which maximum expansion will occur, control that expansion, and assure formation of an effective seal with the well bore wall. For transmitting axial compressive forces from the harder end portions of the sleeve to the intermediate central relatively soft portion, there may be provided axially between the endportions and the soft central portion a pair of essentially annular force transmitting plates, preferably formed of metal and preferably bonded directly to both the hard and soft elastomer. These plates optimize the transmission of axial forces from the hard end portions of the sleeve to the intermediate soft portion, to thereby assure effective radially outward expansion of the latter, and assist in localizing the expansion at the central region of the packer.

An additional feature of the invention resides in a novel method of shaping to a desired circular configuration the outer surface of a packer sleeve section which is formed primarily of soft elastomeric material, such as the soft central section of the above discussed three section sleeve, even though it may be inconvenient or impractical to initially mold the soft elastomer precisely to the desired shape, and is also impossible to subsequently machine the soft rubber to shape after molding. In forming a packer by my method, I first provide the soft elastomer with an outer layer of a harder elastomer, bonded thereto by vulcanization during curing of the soft material, following which the outer harder material may be machined to a precisely predeterminable circular configuration, as by cutting on a lathe or by an appropriate grinding operation. The outer layer thus provided may be thin enough to prevent any substantial alteration of the overall effective hardness of the packer by virtue of the presence of that thin outer layer, and yet because of its presence can enable accurate formation of the packer surface to a proper external shape.

BRIEF DESCRIPTION OF THE DRAWING The above and other features and objects of the invention will be better understood from the following detailed description of the typical embodiment illustrated in the accompanying drawing in which:

FIG. 1 shows a drill string testing assembly utilizing a packer embodying the invention;

FIG. 1a is an enlargement of the packer portion of FIG. 1;

FIG. 2 shows the packer of FIG. 1 in expanded condition;

FIG. 3 illustrates diagrammatically the manner in which the rubber of the packer body is built up on a mandrel;

FIG. 4 is an axial section through the various sections of the packer sleeve while still on the mandrel and,

FIG. 5 shows the sleeve of FIG. 4 while being machined to its ultimate straight cylindrical external shape.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, I have illustrated at 10 an uncased well bore which has been drilled by a bit initially connected to the lower end of a drill string 11. In FIG. 1, the bit has been removed, and there has been connected to the lower end of drill string 11 a drill string testing assembly 12 including a packer unit 13 carrying an apertured pipe 14 adapted to rest on the bottom of the well bore and through which well fluid may flow into the interior of the string.

The packer assembly 13 includes a central vertical externally cylindrical pipe 17 containing a fluid passage 18 through which the well fluid passes upwardly to an upper test portion 19 of the drill string test equipment. At its lower end, pipe 17 is connected rigidly and threadedly to an increased external diameter end element 20, whose lower end is connected to the apertured liner or pipe 14. An essentially annular clamp 21 rigidly connects element 20 to a lower annular packer head or end member 22 which is bonded to the elastomeric packer proper 23. At its upper end, a second annular rigid packer head 24 is bonded to the upper end of elastomeric sleeve 23, so that the elastomeric material of sleeve 23 may be compressed axially between end plates or heads 22 and 24 to cause radial expansion of the sleeve against the well bore wall as indicated in FIG. 2. The two end plates or heads 22 and 24 may be formed of a suitable rigid metal, such as an appropriate steel, and may have reduced diameter axially projecting portions 25 extending into the interior of the elastomeric material for effective bonding thereto. The primary axial forces are transmitted from end plates 22 and 24 through transverse annular force transmitting surfaces 26 on plates 22 and 24. The lower of the two end plates or heads 22 has an annular flange 27 at its lower end by which it is connectible to the previously mentioned clamp 21. Similarly, the upper head 24 has an annular flange 28 at its upper end by which it is con nectible to a clamp 29, which serves to secure upper head 24 rigidly to a flange 30 formed at the lower end of a pipe 31 disposed about the previously mentioned inner pipe 17. 7

Pipe 31 is threadedly connected at 32 to the lower end of a tubular element 33 forming a cylindrical inner chamber 34 within which a nut or enlarged head element 35 carried at the upper end of inner pipe 17 is received. In its lowermost position of FIG. 1, the nut or head 35 is engageable downwardly against the upper end of pipe 31. Upon downward movement of the drill string and the connected elements 33 and 31 relative to inner pipe 17 and its connected parts, end plates 22 and 24 of the packer assembly 13 exert axial compressive force against the rubber or other elastomeric material of sleeve 23.

To now describe in greater detail the construction of the elastomeric packer sleeve 23 proper, this sleeve has a longitudinally central main section 36 and two upper and lower opposite end portions 37 and 38, all vulcanized directly and permanently together to function as an integral flexible unit. Internally, all three of these sections have cylindrical inner surfaces at 39 of a diameter slightly greater than the outer surface of pipe 17, for reception thereabout. Externally, the three sections 36, 37 and 38 have outer cylindrical surfaces 40, which like inner surfaces 39 are centered about the main axis 41 of the tool, and which may be at a diameter corresponding to the maximum diameter of end plates or heads 22 and 24.

The central annular section 36 of packer sleeve 23 is relatively soft in order to allow expansion of that section to a very large diameter for effective sealing engagement with an oversize bore wall, while the upper and lower sections 37 and 38 are formed of harder elastomer'ic material, to prevent excessive expansion of the packer sleeve at those upper and lower locations, and to effectively localize the expansion in a controlled manner at the central region 36.

The central region 36 may itself be formed of materials of two different hardnesses, consisting of an annular main body 42 which is relatively thick radially and forms most of the thickness of the packer sleeve at the region 36, but with a thin radially outer layer or plurality of layers 43 being provided about the periphery of body 36, and with this outer layer being of a harder material than body 36. Preferably, the material forming outer layer 43 is of the same hardness and composition as the upper and lower end sections 37 and 38 of the packer sleeve. The radial thickness of body 36 may be several times as great as the radial thickness of outer layer 43, desirably at least about 22 times its thickness.

Both the inner main body 42 and the outer layer 43 may be both internally and externally cylindrical, or substantially so, and both may terminate at their upper and lower ends in two transverse planes designated 44 and 45 in FIG. 1a.

At the location at which upper harder section 37 of the packer sleeve meets the central softer section 36, there is provided within the sleeve an annular force transmitting and expanding ring 46, formed of a material which is rigid, or at the very least is much harder and more rigid than the elastomeric material of sections 36, 37 and 38, and which is bonded to both of the sections 36 and 37. This ring 46 has a lower face 47 which engages and is bonded to the material of main body 42 of the softer section of the sleeve, and has at its upper side a tapering or flaring surface 48, which advances downwardly or axially as it advances radially outwardly to tend to cam or deflect the material of upper hard section 37 of the packer sleeve radially outwardly upon axial compression of the sleeve. A similar but reversed ring 49 is interposed between lower hard section 38 of the packer sleeve and intermediate section 36, and is bonded thereto. Both of the rings 46 and 49 may be formed of an appropriate metal, such as steel, desirably having its upper and lower surfaces irregularized for optimum bonding of the rubber to these rings.

The inner main body 42 of central section 36 of the packer sleeve is for best results formed of a rubber or other elastomeric material which is so soft that it cannot be easily machined. It is for this reason that the outer harder layer 43 is provided about body 42, in order that the outer layer may be machined accurately to the desired externally cylindrical shape. In the presently preferred arrangement, the material of body 42 has a durometer hardness not greater than about 50, and optimally about 45, while the outer layer 43 and the upper and lower sections 37 and 38 preferably have a durometer hardness between about 65 and 90, optimally about 70. Suitable natural or synthetic rubbers having these hardnesses may be utilized.

With reference now to FIGS. 3, 4 and 5, which illustrate a preferred manner of forming the packer sleeve 23 of FIGS. 1, 1a and 2, the packer sleeve may be built up about, but ultimately removed from, an externally cylindrical forming mandrel represented at 50. This mandrel is composed of a rigid substance capable of withstanding the curing temperature to which the rubber of the packer sleeve must be subjected, and also of a material to which the rubber will not adhere upon vulcanization. For example, mandrel 50 may be formed of standard API steel tubing.

The three main bodies of rubber 37, 38 and 42 of the packer sleeve 23 may be formed on mandrel 50 by winding three elongated strips of thin uncured rubber 37 38 and 42 helically onto mandrel 50 to a proper number of layers to attain the desired thickness of each section. As will be apparent from FIG. 3, the widths of these three strips of rubber correspond to the vertical heights desired for the three sections 37, 38 and 42 in FIGS. 1 and 1a. Prior to winding of these three strips 37', 38' and 42' onto the mandrel, the two rings 46 and 49 may be appropriately located on the mandrel for reception between the different sections of rubber, and the two end plates 22 and 24 may also be appropriately located to have the end sections 37 and 38 wrapped about the cylindrical projections 25 of plates 22 and 24, and be ultimately bonded thereto. As in the case of rings 46 and 49, the surfaces of end plates 22 and 24 which are to engage the rubber are desirably irregularized to assure optimum adherence of the rubber to these elements.

After the three strips 37, 38' and 42 have been wound onto the mandrel to the desired thickness, these three strips are cut, and a short length of another strip is wound onto the central section to form the outer layer 43 of FIGS. 1 and 1a.

With the rubber of all of the sections in uncured state, the mandrel and its carried parts are inserted into an oven at vulcanizing temperature, and the rubber is cured, to vulcanize and integrate the various bodies of rubber into a single unitary elastomeric sleeve tightly vulcanized to the four metal elements 22, 24, 46 and 49. The assembly in this condition is illustrated in FIG. 4, in which the outer surface may not be truly cylindrical in shape. To reduce that outer surface to a precisely cylindrical configuration, the mandrel and carried parts are mounted in a lathe or other machine tool, and are turned while a cutting element 51, or grinder, is engaged with the outer surface of the rubber and moved axially therealong, to machine the outer surface of the hard rubber of sections 37 and 38, and the outer surface of the hard rubber layer 43 of central section 36, to a straight cylindrical uniform diameter condition.

With the sleeve thus fabricated, it is assembled with the other parts of the apparatus in the relationship illus trated in FIGS. 1 and la, and then lowered into the well by drill string 11 to perform a testing operation. When the perforated pipe 16 reaches the lower end of the well bore, its downward movement is halted by engagement with the bottom of the well, and further downward movement of the string causes axial compression of the entire three section sleeve between lower and upper heads 22 and 24, to expand' the packer radially outwardly against the well bore as illustrated in FIG. 2. The relatively hard end sections 37 and 38 of the packer sleeve expand slightly, to an increasing extent as they approach the central soft section 36 of the packer sleeve, but the bulk of the expansion is localized at the central soft section 36 by virtue of the increased hardness of sections 37 and 38. The metal plates 46 and 49 transmit the compressive forces with maximum effectiveness to the central soft region 36, and at the same time facilitate and encourage slight radial expansion of the ends of the harder sections 37 and 38, by virtue of the annular tapering surface 48 on ring 46, and the corresponding surface on ring 49. The thin outer skin 43 on the soft section further assists in controlling the expansion of section 36, but is not thick enough to offer enough resistance to expansion to detract appreciably from the expansion characteristics of the central soft material 42.

While a certain specific embodiment of the present invention has been disclosed as typical, the invention is of course not limited to this particular form, but rather is applicable broadly to all such variations as fall within the scope of the appended claims.

I claim:

1. A weli packer comprising an elongated carrier structure to extend vertically within a well; a tubular resilient packer sleeve disposed about said carrier structure; and two compressing members more rigid than said sleeve at opposite ends of said sleeve and actuable toward one another in a relation compressing said sleeve axially and thereby expanding it radially outwardly to form a seal in the wall; said packer sleeve being externally of substantially circular cross section before expansion; said sleeve including a generally tubular central body disposed about said carrier structure and formed of a relatively soft elastomeric material, and including two generally annular end portions of the sleeve located at and connected to opposite ends of said central body and positioned axially between said central body and said compressing members respectively; said end portions of the sleeve being formed of elastomeric material which is harder than said central body; and said sleeve including an outer layer of elastomeric material disposed about but thinner radially than said central body and formed of an elastomeric material which is harder than said central body and is bonded thereto axially between said end portions of the sleeve.

2. A well packer as recited in claim 1, in which said end portions of said sleeve and said outer layer of elastomeric material have a durometer hardness between about 65 and 90.

3. A well packer as recited in claim 1, in which said central body is formed of an elastomeric material having a dutometer hardness not greater than about 50.

4. A well packer as recited in claim 1, in which said central body is annularly bonded at its opposite ends to said end portions of the sleeve.

5. A well packer as recited in claim 1, including two generally annular metal plates more rigid than the clastomeric material of said central body or said outer layer or said end portions and interposed axially between and bonded to said end portions and said body.

6. A well packer as recited in claim 5, in which said plates have surfaces facing said end portions which are of flaring configuration to advance axially toward said central body as they advance radially outward, and having opposite surfaces facing said central body which extend more directly transversely of said sleeve.

7. A well packer as recited in claim 1, in which said end portions of said sleeve are bonded annularly to said compressing members respectively.

8. A well packer as recited in claim 1, in which said compressing members are bonded annularly to said two end portions respectively of the sleeve, said end portions being bonded essentially annularly to opposite ends of said central body and said outer layer, said outer layer and said end portions being formed of an elastomeric material having a durometer hardness between about 65 and 90.

9. A well packer as recited in claim 8, in which said central body has a durometer hardness not greater than about 50, there being two generally annular metal plates which are more rigid than the elastomeric material of said body or said outer layer or said end portions and are interposed axially between and bonded to said end portions and said body and disposed about said carrier structure, said plates having surfaces facing and bonded to said end portions which are of flaring configuration to advance axially toward said central body as they advance radially outward, and having opposite surfaces facing and bonded to said central body which extend essentially directly transversely of said sleeve. 

1. A well packer comprising an elongated carrier structure to extend vertically within a well; a tubular resilient packer sleeve disposed about said carrier structure; and two compressing members more rigid than said sleeve at opposite ends of said sleeve and actuable toward one another in a relation compressing said sleeve axially and thereby expanding it radially outwardly to form a seal in the wall; said packer sleeve being externally of substantially circular cross section before expansion; said sleeve including a generally tubular central body disposed about said carrier structure and formed of a relatively soft elastomeric material, and including two generally annular end portions of the sleeve located at and connected to opposite ends of said central body and positioned axially between said central body and said compressing members respectively; said end portions of the sleeve being formed of elastomeric material which is harder than said central body; and said sleeve including an outer layer of elastomeric material disposed about but thinner radially than said central body and formed of an elastomeric material which is harder than said central body and is bonded thereto axially between said end portions of the sleeve.
 2. A well packer as recited in claim 1, in which said end portions of said sleeve and said outer layer of elastomeric material have a durometer hardness between about 65 and
 90. 3. A well packer as recited in claim 1, in which said central body is formed of an elastomeric material having a dutometer hardness not greater than about
 50. 4. A well packer as recited in claim 1, in which said central body is annularly bonded at its opposite ends to said end portions of the sleeve.
 5. A well packer as recited in claim 1, including two generally annular metal plates more rigid than the elastomeric material of said central body or said outer layer or said end portions and interposed axially between and bonded to said end portions and said body.
 6. A well packer as recited in claim 5, in which said plates have surfaces facing said end portions which are of flaring configuration to advance axially toward said central body as they advance radially outward, and having opposite surfaces facing said central body which extend more directly transversely of said sleeve.
 7. A well packer as recited in claim 1, in which said end portions of said sleeve are bonded annularly to said compressing members respectively.
 8. A well packer as recited in claim 1, in which said compressing members are bonded annularly to said two end portions respectively of the sleeve, said end portions being bonded essentially annularly to opposite ends of said central body and said outer layer, said outer layer and said end portions being formed of an elastomeric material having a durometer hardness between about 65 and
 90. 9. A well packer as recited in claim 8, in which said central body has a durometer hardness not greater than about 50, there being two generally annular metal plates which are more rigid than the elastomeric material of said body or said outer layer or said end portions and are interposed axially between and bonded to said end portions and said body and disposed about said carrier structure, said plates having surfaces facing and bonded to said end portions which are of flaring configuration to advance axially toward said central body as they advance radially outward, and having opposite surfaces facing and bonded to said central body which extend essentially directly transversely of said sleeve. 